The present invention relates generally to an electromagnetic coupler apparatus and, more particularly to a stripline feedthrough apparatus with an electromagnetic coupling.
The state of the art of electromagnetic coupling apparatus is well represented and alleviated to some degree by the prior art apparatus and approaches which are contained in the following U.S. Patents:
U.S. Pat. No. 4,131,892 to Munson et al. on 26 Dec. 1978; PA1 U.S. Pat. No. 4,170,013 issued to, Black on 2 Oct. 1979 PA1 U.S. Pat. No. 4,197,544 issued to Kaloi on 8 Apr. 1980; and PA1 U.S. Pat. No. 4,486,758 issued to de Ronde on 4 Dec. 1984.
The Munson et al. patent is directed to a stacked antenna structure for the radiation of orthogonally polarized signals utilizing a resonant circularly or ellipitically polarized microstrip radiator wherein the size of the radiator is reduced in the resonant or non-resonant dimensions, or both, without reducing the effective resonant dimension or substantially lowering the efficiency of the radiator. Reduction of the resonant dimension is provided by folding the resonant cavity, while reduction of the non-resonant dimension is facilitated by utilization of a low density, low loss dielectric, such that the loss resistance of the element is appreciable with respect to the radiation resistance of the element.
The Black patent discloses a stripline patch antenna which comprises a conformal antenna having a microstrip patch centered below a slot in a groundplane and covered by a dielectric window and coupled to a stripline feed.
The Kaloi patent describes a microstrip antenna system having two ground planes spaced apart by a dielectric substrate and radiation elements coplanar with one of the two ground planes or sandwiched within the dielectric substrate separating the two ground planes adjacent a window in one of the ground planes. The two ground planes are shorted together in most instances.
The de Ronde patent discusses an antenna element for coupling circularly-polarized radiation to a feedline. The element includes a pair of superposed planar dielectric layers. An outer surface of each layer is covered with an electrically-conductive layer forming a ground plane and having a circular opening defining respective cavities. Orthogonally-crossed dipoles are disposed between the dielectric layers and adjacent the openings for coupling radiation to the feedline through striplines also disposed between the dielectric layers.
Large conformal airborne phased arrays are increasingly projected as a future Air Force need. While many of the ultimate characteristics cannot be accurately predicted at the present time certain features are clearly desirable. One of the features is minimum extrusion to keep added air-drag as low as possible. Because space inside a surveillance aircraft is also at a premium, minimum intrusion is also highly desirable. For these reasons, phased arrays are envisioned with multiple planar configurations, that is, at the outermost plane would be the randome surface, then, the radiating surface, the phase shifter or T/R module surface, finally the beamforming network layer and mixed in within these layers would be DC power and digital control layers.
In order to achieve the above objective the principle concern is the RF feed coupling the RF power distribution network to the active or phase shifter layer. If these feed-throughs are metallic pins and there are a great number of them, both the difficuliy of assembling the networks and the expected power long-term reliability are very serious problems. Furthermore, another set of transverse wire connectors is required for mode suppression making the network assembly even more complex.
In the prior art, the conventional method for connecting one stripline type transmission line to another through multiple layers of dielectric and or conducting planes, consisted of terminating the center conductor of a stripline type transmission line by a pin at right angles to it which then connects to another stripline center conductor that neighbors the first stripline through a hole in the common ground plane (the upper ground plane of the bottom stripline is also the lower ground plane of the upper stripline).
When many layers of stripline are required these pin type connectors become buried (i.e. unacessible from outside). If a solder joint should break or weaken causing an open in the line or, under temperature or physical stress, the pin should short out against the hole in the ground plane, then correction is very difficult and costly. In addition, fabrication of multilayer strip transmission lines with solder connections of this type is both difficult and expensive.
While the above-cited references are instructive, there still remains a need to provide a method to measure the surface temperature of reacting and nonreacting materials. The present invention is intended to satisfy that need.